Field
One or more example embodiments relate to technology for compressing a digital image.
Description of Related Art
A digital image may be a color image or a black-and-white image represented using an infinite digital value set, such as a pixel element or a pixel. The digital image may represent a still image, or a picture image, and may also represent a video image that is a sequence of still images that are displayed in a manner that creates the illusion of motion. Image compression is the technique of applying data compression to digital images.
In general, conventional image compression techniques may be “lossless” or “lossy” depending on whether data is discarded during the image compression process. Examples of the conventional lossless compression technique may include a Huffman encoding technique, an arithmetic encoding technique, and a Fano-Shannon encoding technique. In the lossless compression technique, a decompression process reproduces a complete original image. On the contrary, the lossy compression technique discards a certain amount of data and thus, may provide a further efficiency when compared to the lossless compression technique in terms of processing speed and amount of storage size saved. The lossy compression technique is widely used for video or common image processing. The Joint Photographic Experts Group (JPEG) compression method and the Motion Picture Experts Group (MPEG) compression method are examples of widely used lossy image compression standards.
The JPEG compression method is employed to compress a still image and to transmit a video between users using a video call phone over a public telephone line network of which a transmission band is limited.
In the related art, when compressing a digital image, encoding is performed based on an image quality setting. For example, the digital image is encoded at a user required quality, for example, high, average, low, 88, 90, 92, and the like.
When encoding the digital image based on the image quality setting, raw data that has not been encoded may be encoded to be similar to original data according to an increase in the image quality setting. However, in the case of data having been encoded once or more, only the file size may increase and the further excellent image quality of data may not be guaranteed even after increasing the image quality setting.